The present invention relates to fluorinated compounds usable as additives for hydrogenated resins, for example polyolefins, elastomers and polymers from, polycondensation. The additives of the invention do not negatively affect the processability during the extrusion of hydrogenated resins, on the contrary they improve it and the finished manifactured article shows an improved mould release. Besides, the finished manufactured article (hydrogenated resin added with the invention additives) shows lasting improved surface properties.
More particularly the present invention relates to additives formed by perfluoropolyether chains and functionalized polyolefins. Said additives can be obtained in solid form (granules, powder or pellets) and are compatible with hydrogenated polymers with which they form homogeneous mixtures. Therefore masterbatches at various additive concentrations, even very high, can be prepared, with hydrogenated resins, even of the order of 50% by weight of additive.
In the prior art the use of fluorinated additives to improve the polymer properties is known. U.S. Pat. No. 4,278,776 describes the use of polyamides obtained from perfluoropolyethers as process additives for blends of curable fluorinated rubbers. Tests carried out by the Applicant showed that polyamides obtained from perfluoropolyethers do not allow to prepare masterbatches with hydrogenated resins at high concentration of this additive. Besides even at low concentrations of this additive a homogeneous masterbatch is not obtained. Therefore these masterbatches are not in practice usable in extrusion since finished manufactured articles are obtained having non uniform properties. (See the comparative Examples). U.S. Pat. No. 5,061,759 describes perfluorinated perfluoropolyether additives or having bromine end groups for fluorinated rubbers curable by peroxidic way, the additive amount being in the range 0.5-1% by weight. These additives improve the processability of the fluorinated rubbers and the mould release. Also these additives when used for hydrogenated resins to obtain masterbatches to be used for preparing manufactured articles give the same drawbacks of the polyamides obtained from perfluoropolyethers.
U.S. Pat. No. 3,899,563 describes. monofunctionalized fluoro alkyl additives, such as amides, diamides, triazines, substituted ureas, for thermoplastic resins. In said patent no mention is made to the possibility to prepare masterbatches of above additives with hydrogenated resins, in particular no mention is made to polyolefins.
U.S. Pat. Nos. 5,143,963 and 5,286,773 describe fluorinated additives for hydrogenated thermoplastic polymers. Among the various additives, perfluoropolyether additives are mentioned and only perfluoropolyethers having perfluorinated end groups are exemplified. The additive amount is in the range 0.01%- less than 1% by weight. The finished manufactured articles have a surface tension lower than that of the thermoplastic polymer and show a higher fluorine content on the surface than inside the compound. The manufactured article is characterized by a higher hydrophobicity and antiadherence, a lower friction and a smoother surface. The fluorinated compounds used as additives can be under the form of oil, grease, or rubber. With these additives it is not possible to prepare masterbatches having a high content of additives, for example of 20% (see the comparative Examples). Besides, to additivate the liquid fluorinated compounds, particular equipments must be used so as to have a high mixing efficiency and therefore twin-screw extruders are used. Tests carried out by the Applicant have shown that by using the standard single screw extruders, widely used industrially, it is not possible to prepare masterbatches even at concentrations lower than 1% by weight.
U.S. Pat. No. 5,025,052 describes fluorinated dioxazolidinones as additives for thermoplastic resins. Also in this case no mention is made to the preparation of masterbatches with high additive concentrations.
U.S. Pat. Nos. 5,681,963 and 5,789,491 describe the use of imides based on monofunctional perfluoroalkyl compounds as additives in the production of fibers (polyolefins, polyesters, polyamides) water-repellent, alcohols and fluids having a low surface tension. In said patents it is stated that fluorinated polymer derivatives are not suitable for this kind of use due to their insufficient capability to migrate on the surface. Patent applications WO 97/22,576 and WO 97/22,659 describe the use of mono- and diesters of fat acids, excluding the stearic acid, with monofunctional fluoroalkyl alcohols to give idro/oilrepellent properties to polymer fibres, in particular polypropylene fibres. Also in this case the polymer additives are considered unsuitable as above mentioned.
Patent application WO 99/23,149 describes the preparation of manufactured articles resistant to creaking by addition of a generic fluorinated additive under the form of oil, wax or rubber, in amounts in the range 0.01%-5% by weight, to a hydrogenated polymer such as polyurethane or both thermoplastic and thermosetting resins. Also perfluoropolyethers even having functional end groups, and their homologues having a higher molecular weight, with a fluorine content higher than 50% belong to the class of fluorinated additives. In said patent application it is indicated that when the polymer is thermoplastic, to prepare these compositions the polymer is melted and mixed in the liquid state with the fluorocarbon additive, and the additive feeding into the mixing equipment takes place by addition devices for liquids. Therefore this mixing process shows the drawback to require a particular equipment since the components, as said, must be added at the liquid state. Also perfluoropolyethers having perfluoroalkyl end groups are indicated as usable. Also for said patent application the above same considerations are valid.
Patent application WO 99/23.148 describes manufactured articles resistant to abrasion obtained by addition of 0.01% up to 1% of one of the fluorinated additives described in the previous patent application for thermosetting resins. No reference is made to masterbatches.
Patent application WO 99/23,147 describes linear or crosslinked polymers having a Shore A hardness from 10 to 90, modified by addition of fluorinated additives in amounts between 1 and 10%, to obtain an improved abrasion resistance. In above patent application fluorinated additives oils, rubbers or greases formed by fluorocarbons which can contain functional groups are indicated as suitable. The mixing equipment is the one used to mix liquid compounds described in patent application WO 99/23,149 and therefore also this mixing process shows the same above mentioned drawback.
U.S. Pat. No. 5,451,622 describes the use of partially fluorinated piperazines with monofunctional fluoroalkyl segments, containing a fluorine amount between 20 and 70% by weight as hydro/oilrepellent additives for hydrogenated resins, such as for example polypropylene. Also in said patent no mention is made to masterbatches having a high concentration of additive.
Generally according to the above prior art the fluorinated additives can be used as process additives, or as additives to give improved surface properties to the finished manufactured article. The addition procedure of the fluorinated additive into the hydrogenated resin is generally a complicated step and requires, as seen, particular equipments for the dosage of the fluorinated additive in extrusion. The additive indeed is often under the liquid form and high efficiency equipments as twin-screw extruders for the homogeneization with the resin are required. With the liquid fluorinated additives of the prior art it is difficult to prepare masterbatches having a high additive concentration in the hydrogenated resin, in particular at concentrations higher than 10% by weight of additive. When perfluoropolyethers are used as additives, masterbatches having a maximum concentration of additive of 1-2% by weight can be prepared. (See comparative Examples). This is due to the substantial immisciability of the fluorinated additive with the hydrogenated resin which requires the use, as seen, of particular equipments. The lack of homogeneity in the masterbatch implies a difficult dosage of the additive in the final manufactured article, with the obtainment of manufactured articles which have no reproducible properties. This is a drawback from the industrial point of view. A further drawback is represented by the limited permanence in the time of the fluorinated additive in the manufactured article. In fact the additive can be removed by thermal effect during the working steps, or byxe2x80x94washing away, or by mechanical action, for example abrasion, with loss of the surface properties of the manufactured article and possible environmental pollution. At any rate no mention is made to masterbatch of additive in hydrogenated resin with high additive content, of the order of 50%. The possibility to have available masterbatches with a high content of additive allows to have masterbatches with a more uniform concentration of additive. Furthermore said masterbatches can be used with hydrogenated resins even different from those used to prepare masterbatches. This allows to obtain final resins having a more uniform distribution of the additive and therefore with substantially homogeneous properties and thus lower wastes during the production of manufactured articles.
The need was felt to have available fluorinated additives having the following properties:
were available in solid form (granules or pellets), and therefore measurable with normal loading hoppers, without necessarily requiring the use of particular batcher,
were easily compatible with the hydrogenated resins, both thermoplastic and thermosetting, for example polyolefins, polyolefin rubbers, polyesters, polyamides, polyurethanes, also using single screw extruders,
confer to the finished compound lasting surface hydro- and oilrepellence properties, abrasion resistance, low friction coefficient, improved mould release,
possibility to prepare masterbatches at various, even very high, additive concentrations, with hydrogenated resins, even of the order of 50% by weight of additive.
The Applicant has surprisingly and unexpectedly found additives containing perfluoropolyether oligomers or polymers and functionalized polyolefins, having the combination of the above properties.
An object of the present invention are additives for hydrogenated resins, formed by functionalized perfluoropolyethers and functionalized polyolefins, said additives obtainable by using the following components:
a) bifunctional perfluoropolyethers having a xe2x80x94COOR end group, optionally in admixture with monofunctional perfluoropolyethers having xe2x80x94COOR end group, wherein Rxe2x95x90H, C1-C10 alkyl, the number average molecular weight of bifunctional and monofunctional perfluoropolyethers being in the range 500-5,000, preferably 900-3,000;
b) mono, bi or polyfunctional hydrogenated monomers having functional groups capable to react with the xe2x80x94COOR end groups of compound a); preferably said functional groups of the hydrogenated monomers are aminic groups,
c) polyolefins having functional groups, preferably formed by C2-C4 monomers, wherein said functional groups are capable to react with the block oligomer/polymer obtained by reaction of a) with b), preferably said functional groups being obtained by grafting with maleic anhydride;
reacting in a first step a) with b), or a) with mixtures of monomers b) having a different functionality, until disappearance of the xe2x80x94COOR group of component a), and in a second step the product obtained from the reaction of a) with b) with the functionalized polyolefins c).
The additive of the invention can optionally comprise neutral perfluoropolyether oils having a molecular weight in the range 2,000-10,000 (compound d)).
The amounts of each of the components a) -d), expressed as percentages by weight, are the following:
component a) 30-70% by weight;
component b) 1-30% by weight;
component c) 10-70% by weight;
component d) 0-20% by weight;
the sum of a)+b)+c)+d) being equal to 100% by weight.
The bifunctional (per)fluoropolyethers and the monofunctional perfluoropolyethers (component a)) have one or more of the following units statistically distributed along the chain: (C3F6O); (CFYO) wherein Y is F or CF3; (C2F4O); (CF2(CF2)xxe2x80x2CF2O) wherein xxe2x80x2 is an integer equal to 1 or 2; (CR4R5CF2CF2O) wherein R4 and R5 are equal or different from each other and selected from H, Cl, and wherein one fluorine atom of the perfluoromethylene unit can optionally be substituted with H, Cl or (per)fluoroalkyl, having for example from 1 to 4 carbon atoms.
The preferred bifunctional compounds of a) are the following with the perfluorooxyalkylene units statistically distributed along the chain:
(axe2x80x2)xe2x80x94CF2xe2x80x94Oxe2x80x94(CF2CF2O)pxe2x80x2(CF2O)qxe2x80x2xe2x80x94CF2xe2x80x94xe2x80x83xe2x80x83(VIII)
wherein:
pxe2x80x2 and qxe2x80x2 are numbers such that the qxe2x80x2/pxe2x80x2 ratio is comprised between 0.2 and 2 and the number average molecular weight is in the above range;
xe2x80x83(bxe2x80x2)xe2x80x94CFXxe2x80x2Ixe2x80x94Oxe2x80x94(CF2CF(CF3)O)rxe2x80x2xe2x80x94(CF2CF2O)sxe2x80x2xe2x80x94(CFXxe2x80x2IO)txe2x80x2xe2x80x94CFXxe2x80x2Ixe2x80x94xe2x80x83xe2x80x83(IX)
wherein:
Xxe2x80x2I is xe2x80x94F or xe2x80x94CF3; rxe2x80x2, sxe2x80x2 and txe2x80x2 are numbers such that rxe2x80x2+sxe2x80x2 is in the range 1-50, the txe2x80x2/(rxe2x80x2+sxe2x80x2) ratio is in the range 0.01-0.05, rxe2x80x2+sxe2x80x2 being different from zero, and the molecular weight is in the above range;
(cxe2x80x2)xe2x80x94CF(CF3)(CFXxe2x80x2IO)txe2x80x2(OC3F6)uxe2x80x2xe2x80x94ORxe2x80x2fOxe2x80x94(C3F6O)uxe2x80x2(CFXxe2x80x2IO)txe2x80x2CF(CF3)xe2x80x94xe2x80x83xe2x80x83formula (X)
wherein:
Rxe2x80x2f is a C1-C8 perfluoroalkylene; uxe2x80x2+txe2x80x2 is a number such that the number average molecular weight is in the above range; txe2x80x2 can also be equal to zero; Xxe2x80x2I is as above indicated;
(dxe2x80x2)xe2x80x94CF2CF2Oxe2x80x94(CF2(CF2)xxe2x80x2CF2O)vxe2x80x2xe2x80x94CF2CF2xe2x80x94xe2x80x83xe2x80x83(XI)
wherein:
vxe2x80x2 is a number such that the molecular weight is in the above range, xxe2x80x2 is an integer equal to 1 or 2;
(exe2x80x2)xe2x80x94CF2CH2xe2x80x94(OCF2CF2CH2O)wxe2x80x2xe2x80x94ORxe2x80x2fOxe2x80x94(CH2CF2CF2O)wxe2x80x2xe2x80x94CH2CF2xe2x80x94xe2x80x83xe2x80x83(XII)
wherein:
Rxe2x80x2f is a C1-C8 perfluoroalkylene; wxe2x80x2 is a number such that the number aaverage molecular weight is in the above range; the end groups of the bifunctional perfluoropolyethers component a) being of the xe2x80x94COOR type wherein Rxe2x95x90H or C1-C10 alkyl.
The bifunctional (per)fluoropolyoxyalkylenes are known products and can be prepared starting from the corresponding (per)fluoropolyoxyalkylenes having xe2x80x94COF end groups (see for example patents GB 1,104,482, U.S. Pat. Nos. 3,715,378, 3,242,218, 4,647,413, EP 148,482, U.S. Pat. No. 4,523,039, EP 340,740, patent application WO 90/03357, U.S. Pat. No. 3,810,874, EP 239,123, U.S. Pat. Nos. 5,149,842, 5,258,110).
The preferred monofunctional perfluoropolyethers which are used in a) in admixture with bifunctional perfluoropolyethers have the following structures:
Axe2x80x94O(C3F6O)m(CFYO)nxe2x80x94xe2x80x83xe2x80x83IB)
wherein
Y is xe2x80x94F, xe2x80x94CF3; Axe2x80x2=xe2x80x94CF3, xe2x80x94C2F5, xe2x80x94C3F7, xe2x80x94CF2Cl, C2F4Cl;
the C3F6O and CFYO units are randomly distributed along the (per)fluoropolyether chain, m and n are integers, the m/n ratio is xe2x89xa72, m and n have values such that the molecular weight is within the limits indicated for component a);
C3F7O(C3F6O)mxe2x80x94xe2x80x83xe2x80x83IIB)
wherein m is a positive integer and is such that the average molecular weight is in the limits indicated for component a);
(C3F6O)m(C2F4O)n(CFYO)q xe2x80x83xe2x80x83IIIB)
wherein:
Y is equal to xe2x80x94F, xe2x80x94CF3; m, n and q, different from zero, are integers such that the number average molecular weight is in the limits indicated for component a);
being the end group of the monofunctional perfluoropolyethers xe2x80x94CF2xe2x80x94COOR, R being as above.
The compounds IB) are for example obtainable by photooxidation of hexafluoropropene according to the process described in patent GB 1,104,482; the compounds IIB) are for example obtainable by ionic telomerization of hexafluoropropene epoxide: see for example U.S. Pat. No. 3,242,218; the compounds IIIB) are for example obtainable by photooxidation of C3F6 and C2F4 mixtures by the processes described in U.S. Pat. No. 3,665,041.
The amount of monofunctional perfluoropolyethers in admixture with the bifunctional perfluoropolyethers is in the range 0-90% by weight of the mixture a), preferably 5-40%.
Examples of component b), when the functionality is aminic, are the following:
(b1) monoamines of formula R1-NH2 wherein R1 is a linear aliphatic or cycloaliphatic C1-C20 alkyl with a number of carbon atoms of the ring from 4 to 6, optionally substituted with C1-C4 alkyl groups; or R1 is an aryl group optionally substituted with linear or branched C1-C4 alkyl groups, the total number of the carbon atoms being in the range 6-20; an example of the amines of formula R1xe2x80x94NH2 is stearylamine;
(b2) diamines of formula NR2AR3Axe2x80x94R1Axe2x80x94NH2, wherein R1A=linear or cycloaliphatic C2-C12 alkyl radical with a number of carbon atoms of the ring from 4 to 6, optionally substituted with C1-C4 alkyl groups, or C6-C12 aryl group; R2A and R3A, equal to or different from each other, are hydrogen or linear or branched C1-C5 alkyl group; examples of diamines with R1A=alkyl and R2A=R3A=H, are ethylendiamine and hexamethylendiamine; an example of diamine with R1A=aryl is naphthalendiamine; an example of diamine with R1A=alkyl and R2A=R3A=CH3 is N,N-dimethylamino-ethylendiamine;
(b3) aromatic tetramines of formula (NH2)2xe2x80x94Ar1-Ar1-(NH2)2 with Ar1=phenyl, optionally substituted with C1-C4 alkyl groups; an example of aromatic tetramine is the tetramino biphenyl compound.
The preferred monomers b) are stearylamine (b1), still more preferably a compound of the classes (b2) and (b3).
In the component c) the functionalized polyolefins are for example the following polymers: polypropylene homopolymer, copolymers of polypropylene, high density polyethylene (HDPE), linear low density polyethylene (LLDPE) grafted with functionalized monomers capable to react with the aminic groups of the reaction product of a)+by. As an example of grafting monomer the maleic anhydride can be mentioned. Other components c) are copolymers or terpolymers of ethylene containing an ethylenic monomer having a second functional group, for example with vinyl acetate, and optionally in the presence of carbon oxide CO, for example EVA, E/nBa (n-buty-lacrylate) and E/nBA/CO.
The functionalized polyolefins component c) are commercially known and available products. For example the resins Fusabond(copyright) and Bynel(copyright) (DuPont), and the resins Questron(copyright) (Montell) can be mentioned.
The perfluoropolyether oils component d) have the same composition of units in the chain as described for component a), but they have perhalogenated end groups of the xe2x80x94CF2X type, with X=F, Cl, preferably X=F. Said perfluoropolyethers are obtainable by known processes. See for example U.S. Pat. Nos. 3,665,041, 2,242,218, 3,715,378 and EP 239,123.
Admixtures of monomers b) having the same chemical function, for example stearylamine with hexamethylendiamine, can be used in the invention composition.
The additives according to the present invention are obtainable by a process comprising the following steps:
1) synthesis of the compound a)+b) by reaction of the functionalized perfluoropolyether component a), optionally formed by a mixture of a bifunctional and monofunctional perfluoropolyether, with the hydrogenated monomer component b), by heating under stirring at a temperature in the range 90xc2x0-100xc2x0 C., and subsequently at 100xc2x0-130xc2x0 C. under vacuum (1 mmHg) to complete the reaction, i.e. until in the IR spectrum the band at 1800 cmxe2x88x921 of the COOR group linked to xe2x80x94CF2xe2x80x94 disappears;
2) addition, under stirring, in the same reactor, of the functionalized polyolefin component c), preferably functionalized with maleic anhydride, and reaction of the mixture by heating at atmospheric pressure for 30-60 minutes at a temperature in the range 180xc2x0 C.-190xc2x0 C.; at the end hot discharge of the obtained product.
Step 1 is carried out by introducing in a polycondensation reactor, or in suitable mixing cell, equipped with stirrer, a mixture formed by the following components:
compound a), for example an ethyl or methyl diester of a perfluoropolyether, optionally in admixture with a perfluoropolyether monoester,
monomer b), optionally in admixture with other monomers b) having a different functionality; for example as component b) an aliphatic or aromatic diamine, optionally in admixture with monofunctional and/or polyfunctional amines having functionality higher than two, can be used;
the molar ratio between the functional groups of b) and a) is in the range 1-1.5, and anyway the amount of b) must be such to cause in the reaction the disappearance of the xe2x80x94COOR groups of a). The temperature of the reactor is then brought to a value in the range 90xc2x0-100xc2x0 C., under stirring, collecting by distillation the released alcohol. When the distillation phase at atmospheric pressure is over, the polymer is heated to 100xc2x0-130xc2x0 C. under vacuum (1 mmHg) to complete the reaction. The reaction ends when in the IR spectrum the band at 1800 cmxe2x88x921 of the COOR group linked to xe2x80x94CF2xe2x80x94 disappears.
The ratio between the monofunctional monomers and polyfunctional monomers of b) can be optimized in function of the molecular weight of a)+b) one wants to obtain.
The monomers b) react with the bifunctional perfluoropolyethers a), optionally in admixture with monofunctional perfluoropolyethers, giving for example polyamides and polybenzoimidazoles, the latter obtainable from the above mentioned aromatic tetramines (b3).
Optionally, to the compound obtained in the first step, fluorinated additives, such as for example the perfluoropolyether oil compound d) can be hot added, under stirring, in the amounts by weight within the above range.
In step 2) component c), the functionalized polyolefin, preferably with maleic anhydride, and the reaction product of a) with b) are introduced in the same reactor under stirring. It is heated at atmospheric pressure under stirring for 30-60 minutes at a temperature of 180xc2x0C.-190xc2x0 C.; the discharged finished reaction product is a mass of homogeneous plastic material. In the second step the ratio between the functional groups of the compound obtained by reaction of a) with b) and the functional groups of the functionalized polyolefin ranges from 10 to 0.1 by moles, preferably it is about 1.
The additive obtained at the end is under solid form at room temperature and higher, generally up to 80xc2x0 C., being characterized by a melting point generally higher than 80xc2x0 C., and by a perfluoropolyether content in the chain higher than 50% by weight.
The so obtained invention additive, preferably after extrusion and pelletization, is used as additive to obtain homogeneous masterbatches with hydrogenated resins. The additive concentrations in the masterbatch are in the range 1-50% by weight.
Examples of hydrogenated resins are polyolefins such as HDPE, LLDPE, PP and respective copolymers, polyesters such as PET, polyamides as nylon, rubbers such as EPDM, etc.
The masterbatches are prepared for example by mixing the additive with hydrogenated resins, for example in a mixing cell, at temperatures in the range 170xc2x0 C.-190xc2x0 C. for 15-30 min, or by extrusion, under the operating conditions used for the hydrogenated resins.
Optionally, the product obtained from the reaction of component a) with component b) of the additive and then reacted with the component c) can be added to the hydrogenated resin.
For example, the reaction product of a)+b) can be added in a mixing cell or extruder to the hydrogenated resin and then the two phases compatibilized during the extrusion by adding granules of component c). The masterbatches are macroscopically homogeneous and defects free. It is industrially advantageous to have available masterbatches having a high additive concentration. In this case the masterbatch is used by adding the hydrogenated resin, in subsequent dilutions, until obtaining the desired fluorine content. During this processing, losses of additive or its components have not been noticed.n
According to a non binding theory, it is considered that the fluorinated part, the perfluoropolyether compound a) chemically linked to the polyolefin c) cannot be extracted during the steps of the obtainment of the masterbatch. Besides, it has been found that the additive is not volatilized with the mentioned thermal treatments.
The finished manufactured article obtainable by mixing the masterbatches with hydrogenated resins is characterized by the combination of the above properties: hydrophobicity, resistance to low surface tension liquids, resistance to abrasion, and low friction coefficient, and maintenance of these properties in the time.
A further advantage of the invention additive unexpectedly found by the Applicant is that it can be used also to carry in the hydrogenated resin other fluorinated additives, such as non functionalized perfluoropolyether oils (component d)), without requiring the use in extrusion of liquid batchers, obtaining an improved final homogeneity and persistence of the perfluoropolyether oil, in the manufactured article in use. Indeed, as said, a drawback of the use of non reactive perfluoropolyether oils as additives for hydrogenated resins is that their effect on the hydrogenated resins is very limited in the time.
The additive of the present invention is characterized by its rheological properties, thermal analysis (differential calorimetry and thermogravimetry) and IR spectroscopy.
As already said, the additive of the invention improves the processing properties and confers also properties of improved mould release from the of the finished manufactured article.
The manufactured article can be subjected to a second thermal treatment by heating at a temperature in the range 100xc2x0-140xc2x0 C. to further improve the above mentioned surface properties.
The following Examples illustrate the invention without limiting the scope thereof.